High frequency words, also referred to as sight or key words are simply common words found in text. Just 16 words (a, and, he, I, in, is, it, my, of, that, the, then, to, was, went, with) make up a quarter of all the words in a typical text and that a total of 100 words (including the 16 most common) represent half the words in a text. Learning these "high frequency words" can give your child a head start in learning to read.